Existing drug offers new hope in a subtype of pancreatic cancer

A new use for an old drug shrinks a particular type of pancreatic cancer and stops it from spreading, according to new research.

"This is incredibly important research showing for the first time that there's potential to tailor treatment to pancreatic cancer patients based on differences in their tumor's genetic fingerprint. It's a crucial step forward in developing new treatments for this devastating disease," said study author Jennifer Morton, PhD.

The scientists, at the Cancer Research UK Beatson Institute and the University of Glasgow in the United Kingdom, treated mice with pancreatic cancers caused by known genetic faults with the drug rapamycin. Their study was published in Gut (2014; doi:10.1136/gutjnl-2013-306202).

Previous clinical trials did not find this drug to be effective as a treatment for pancreatic cancers when it was given to all patients with different forms of the disease. However, the team's findings show that a particular type of pancreatic tumor may be responsive to the drug after all. This type of tumor is caused by a fault in the gene PTEN, which is involved in cell growth.

The researchers found that giving rapamycin to mice with faulty PTEN pancreatic tumors stopped the cancer cells from spreading. In some cases the drug also caused the tumor to shrink.

The drug blocks the protein mammalian target of rapamycin (mTOR), which also controls cell growth. The research suggests that tumors caused by the faulty PTEN gene may be dependent on mTOR to keep growing.

An analysis of a sample of human pancreatic tumors by the team found that approximately 1 in 5 carried a faulty PTEN gene, giving hope that a substantial number of patients could benefit from treatment with rapamycin.

"Although it's at a very early stage, it's the first time we've been able to pinpoint a genetic fault in pancreatic cancers and match it up with a specific drug,” said Morton. "While more research is needed to see if this approach could benefit patients, it's a crucial step forward in developing new treatments for this devastating disease, which has seen no survival improvements since the 70s."

The scientists also used a new type of imaging to help them see if the drug was working early on in the treatment, which may help doctors in the future monitor if the patient is responding.